1. Field of the Invention
This invention concerns pipe clamps and more particularly clamps of the saddle type in which a U-bolt member is slidably received in eyes on opposite sides of the saddle member with the interior curvature of the U-bolt and a corresponding interior curvature on the saddle member providing an opening within which the pipes to be clamped are received. Tightening of the U-bolt is accomplished by means of nuts threadably engaging the U-bolt ends, with a clamping pressure thus applied about the pipe periphery.
2. Description of the Prior Art
Such saddle clamps are in near universal use in the clamping together of various sections of automotive exhaust systems, i.e., exhaust pipe, muffler, and tailpipe sections, etc., and are of the construction described above, i.e., with a U-bolt member cooperating with a saddle member to clamp the various joints of the system together. Due to the production volume involved in automotive markets, the cost of construction of the clamp is paramount and in minimizing the cost, it is highly desirable to utilize the simplest possible manufacturing steps and most efficient use of material. Since the U-bolt itself is of maximum simplicity and efficiency in terms of the material usage, the saddle member is the element in which careful design is likely to achieve cost savings. In achieving such maximum efficiency of material and simplicity of manufacturing techniques, the performance requirements of the clamping unit must of course not be compromised. This performance must include adequate rigidity of the saddle member to resist the distorting force generated by assembly of the clamping unit, care being taken that a design does not impose asymmetrical forces such that bending distortion of the saddle member takes place upon tightening of the U-bolt nut and that the structural configuration of the saddle member is such as to afford maximum rigidity along the direction to which the forces are applied. The clamping pressure in these applications generates a sealing deformation of the pipes which are to be clamped along the interior edge of the saddle clamp as well as of the U-bolt radius. The clamping action is accomplished upon the achievement of sufficient distortion or deflection of the joints to generate the desired tight fit between the joined pipe sections.
The rigidity of the saddle member of course must be adequate to resist the force levels which are necessary to be developed in order to carry out the deforming of the pipe sections. Such forces are largely dependent on the surface pressure which can be applied by the saddle clamp member if the surface area engaging the pipe sections is relatively large, the force levels required for adequately deforming the pipe sections is relatively high necessitating a relatively massive saddle member.
Another requirement which must be met is that of a minimum outside envelope of the assembled U-bolt saddle clamp configuration since clearance is ofter very limited in such applications between surrounding automotive body structures. The design of the saddle member should thus be such that while being of maximum rigidity in the direction of application of the forces, it does not increase the envelope of the assembled clamp.
Finally, the manufacturing method used to form the clamping member of course should be as simple as possible to achieve the aforementioned design requirements so as to minimize the cost of fabrication.
While pressure ridges have heretofore been recognized as desirable and indeed have been incorporated in similar pipe clamps, generally the pressure ridge has been created by one of three different expedients. In the Brown U.S. Pat. No. 3,040,407 the use of a wire form and/or a stamped ridge is disclosed to increase the unit pressure on the clamp pipe. This general approach is also disclosed in the Graham et al U.S. Pat. No. 2,959,834, Koehler U.S. Pat. No. 3,178,208, Power et al U.S. Pat. No. 3,222,090 and Engman et al U.S. Pat. No. 3,900,933. However, these saddle configurations are relatively massive to accommodate the presence of an integral pressure ridge. If a wire form pressure ridge is used with a light duty saddle construction the resulting clamping assembly is not able to resist the relatively high clamping pressure as is required for clamping exhaust system components together. The relatively massive saddle configurations involve relatively large amounts of material and are expensive to manufacture.
Riker U.S. Pat. No. 2,719,345 shows a chamfering of the ends of a layered sheet metal saddle to increase the unit clamping pressure. Such chamfering involves an extra manufacturing step and again would appear to create a possibility that a sharp edge could result which could cause splitting of the clamped pipe side walls.
This patent, as well as the Osborn et al U.S. Pat. No. 3,192,593, the Spotts et al U.S Pat. No. 3,605,214, the Dowling et al U.S. Pat. No. 3,879,815 and the Heckethorn U.S. Pat. No. 3,955,250 all show layered sheet metal type saddle construction, which while an efficient form of construction, does not show a satisfactory pressure increasing configuration such that assembly requires a high torque level to be exerted on the nuts necessitating relatively heavy U-bolt and saddle specifications to withstand the high forces required.
Accordingly, it is an object of the present invention to provide a pipe clamp of the type including a U-bolt and saddle member assembly in which the saddle member is configured to minimize the distorting forces applied on the saddle member, to minimize the amount of material which must be utilized.
It is another object of the present invention to provide such a saddle clamp assembly in which the pressure which is to be applied on the joint pipes by the saddle is maximized so as to reduce the clamping pressure or forces which must be developed by the clamping assembly in providing the final assembled pipe joint.
It is a further object of the present invention to provide such a clamping assembly saddle member which is formed by a simple, low cost method of manufacture while providing the aforementioned required rigidity to the forces generated during installation.